Skating not dependent on smoothness of ice, 260; history of,
273.
Skating only possible on very few substances, 279.
Soddy, F., on isotopes, 24.
Sodium, deficiency of, in sediments, 44; discharge of rivers,
14.
Soils, formation of, 37-39; surface area exposed in, 39.
Sollas, W. J., age of Earth by sodium in ocean, 14; thickness of
sediments, 6.
Spencer, on division of protoplasm, 67.
Spores, number of molecules in, 97.
Stevenson, Dr. Walter C., and technique of radioactive treatment,
259.
Stoletow, photo-electric activity anal absorption, 207.